PeriFIG 3: Basal laminae (BL) covering the germ line are separate from the rachis coat.
A. The pseudocoelomic body cavity is lined by the BL (orange) of the gonad, intestine, hypodermis and bodywall muscles. In distal gonad, the syncytium of proliferating germline cells with incomplete cleavage furrows surround a cytoplasm-filled core, the central rachis. The rachis is reduced in proximal gonad. TEM, transverse section of the anterior body. Bar, 1μm. (Image source: [Hall] N501A.)
B. Same distal gonad image as in A, magnified. The gonad BL covers the outside of the germline completely, even where the sheath is incomplete. A lattice of hemicentin tracks (dark orange lines over the TEM image) line the rachis. (Blue lines) Germline cell borders. More proximally, the rachis of maturing oocytes is lined by a uniform sheet of hemicentin (not shown).
C. Hemicentin is concentrated in the apical spaces that surround the rachis and is absent from the lateral spaces along germline plasma membranes. The hemicentin lining may restrict bulk cytoplasm flow through the rachis into the more mature oocytes in the most proximal regions of the gonad (Vogel and Hedgecock, 2001). TEM, longitudinal section. (Image source: [Hall] N533-121.)
Click on picture for full resolution image.